The present invention relates to a sliding piston joint of hydrostatic piston machines.
A sliding piston joint of a hydrostatic machine has been proposed, in which a hydrostatic pressure field is developed at a base portion of the sliding shoe and communicates with a recess or cavity of a piston through a passage which is formed in the sliding shoe and in a head portion of the piston. Such a joint is disclosed in the U.S. Pat. No. 4,018,137. In this case a small quantity of pressure fluid is supplied from a high pressure side of the hydrostatic piston machine into the hydrostatic pressure field so as to hydrostatically relieve the sliding shoe. This has a disadvantage that a certain quantity of pressure medium is always being lost, and that a hydrostatic pressure field must be developed at the sliding shoe. Furthermore, the communication of the cavity with the piston receiving passage results in that during the suction stroke insufficient quantity of pressure fluid is supplied for relief of the piston.